Development and validation of a generalized modeling approach for islanded inverter-based microgrids with static and dynamic loads

State-space modeling approaches have been extensively used in stability studies of the conventional power system. These stability studies involve the development of state-space models of different components of the power system and then linearizing them around a steady-state or an equilibrium point and combining them on a common DQ reference frame. In this paper, a similar approach has been proposed to develop a generalized modeling approach for islanded inverter-based microgrids (IIMGs) with static and dynamic loads. The proposed generalized modeling approach divides the whole IIMG system, virtually, into three sub-modules such as generation sub-module, network sub-module, and load sub-module. The load sub-module is further divided into passive, active and dynamic load sub-modules. To obtain the complete model of the IIMG system, all the individual sub-modules are modeled in a local dq reference frame and then combined on a common DQ reference frame. The developed model includes both low as well as high-frequency dynamics of IIDG units, network dynamics, and load dynamics. Eigenvalue analysis and time-domain simulations have been performed to validate the linearized and non-linear models, respectively, obtained from the proposed generalized modeling approach. The simulation results revealed the applicability of the proposed generalized modeling approach for stability studies and to find out the causes behind the excitation of a particular mode, which play an important role in the design of a proper controller to mitigate the unstable oscillations.